View -> Toolbars -> Customize requires drag and drop, which requires a mouse. Keyboard users cannot use it. On the other hand, keyboard users can't use the toolbar anyway, so this is not a high priority. Technically, it could be argued that it is a section 508 bug, so I'm filing it.

Just got someone in #firefox that wants to hide the search bar because it sometimes truncates the address bar. Also users can hit the url bar and search bar with the keyboard so those two things are at least a problem. Maybe solved by creating some sort of keyboard accessible toggle (about:config?) for things that can be hit with the keyboard.

No, just make the customize toolbar feature key navigable.

looks like [alt]View->Toolbars->Customize with their access keys does it..

There's no way to do the actual customizing, though...

My window manager doesn't allow drag and drop, so it is impossible to add, remove and change the position of icons in the Navigation Toolbar.

Is it possible to edit a file in the profile folder to customize the toolbar?

Firefox has stopped using this feature and now has its own customizable toolbars page... which is also not keyboard accessible. Someone else then filed a bug about that (bug 1116578), and so because one of these has to go to toolkit (no use keeping both around just for Firefox and 0 for toolkit), it seems more logical to move this one as that's what this bug was always about.